Hypo eliminator solution



Patented Jan. 4,- 1944.

HYPO ELIMINA'I'OR. SOLUTION 3 Lowell E. Muehler, Rochester, N. Y.,assignor to Eastman Kodak Company, Rochester, N. Y., a

corporation of New Jersey .1 No Drawing. Original application September30,

1941, Serial No. 413,001.

Divided and this application September 30, 1941, Serial No. 413,002

7 6 Claims.

This invention relates to solutions for use in the elimination of hypofrom photographic images;

This application is a division of U. S. patent application Serial No.413,001, filed September 30, 1941. v

In the processing of photographic developingout' materials such asgelatino-silver halide emul-' sions coated on paper, film, or glasssupports, if after fixation, the hypo (sodium or ammonium thio'sulfate)is not completely eliminated from the processed material by washing orother means, under suitable conditions of temperature and humidityduring storage, the silver image will tend to fade. This change involvesconversion of some of the silver to less visible yellowish silversulfide.

When one uses alkaline aqueous solutions containing compounds which formcomplex silver compounds, such as solutions of ammonia or amines, forthe purpose of treating fixed paper prints, films, and'plates to assistin the removal of the thiosulfate compounds during the treatment or insubsequentwashing, or to act in conjunction with hydrogen peroxide insuitable concentrations for sufliciently oxidizing the thiosulfate toneutral sulfate,it is found that the tone of the images, particularlythose of finegrain materials such as prints, is altered from a warmblack to a more bluish-black in the low and intermediate densities andto a warmer or less dense black in 'the higher densities. This effectwhile desirable for certain purposes is, by virtue of the alteration intone, sometimes undesirable.

It has been found that this alteration of tone can be decreased, and insome cases prevented by adding to the ammonia or amine-containingsolution a soluble compound which is capable of forming silver compoundswhich are insoluble or slightly or difiicultly soluble in the ammonia oramine solution. Suitable compounds in all such solutions including thosecontaining hydrogen peroxide, are alkali metal halides, such aspotassium bromide and potassium iodide. The halide acids, hydrol 'omicand hydricdic, and their soluble ionizable \lts with ammonia, organicamines, and other org .nic compounds may also be employed in place ofthe alkali metal bromides and iodides. In addition, organic reactantsfor silver are also effective,

The method used for treating prints in the manner of my inventionincludes: washing the fixed prints for about 10 to minutes, treatingwith the alkaline peroxide solutions for 5 to 10 minutes, and washingfor 5 to 10 minutes. In case alkaline solutions containing no peroxideare used, the prints may either be washed or not washed prior totreatment, as desired. Treatment may be from 2 to 10 minutes followed bysufficient washing, 'for example, about 30 minutes. The degree ofelimination of hypo depends both upon the time of treatment and thedegree of washing.

The following examples show typical solutions which may be usedaccording to my invention, however, these examples are intended to beillustrative only, and are'not exhaustive of the variations andequivalents contemplated by my ii vention.

Example 1 Water Cc 500 Hydrogen peroxide (3% solution) cc -500 Ammoniacc 10 Potassium bromide "grams" 1-- 10 Water to make liter' 1 The amountof bromide in the above formula is not critical, however, the indicatedrange gives satisfactory results. In case it is desired touse potassiumiodide in place of bromide, about 0.1 to about 2.0 grams issatisfactory.

The following organic reactions for silver may be substituted forbromide or iodide in the above example: a

Grams 1,2,3-benzotriazole 0.1-1.0 5-(or 6-)bromobenzotriazole 0.1-1.06-nitrobenzimidazole 0.1--0.5 5-(or 7) nitroindazole 0.1-0.5S-aminotetrazole 0.1-1.0 2-aminobenzothiazole 0.1-1.02-acetylaminobenzothiazole 0.1-0.5

The organic compounds may be added as alco-' hol solutions or in theform of their water soluble salts. When sufliciently soluble in watersuch as with benzotriazole, they may be added directly.

Example 2 Water liter 1 Ammonia (28 per cent) cc 5-25 To this solutionmay be added any One of the following:

Grams Potassium bromide 1-10 Potassium iodide 0.1- 2G-nitrobenzimidazole 0.1- 0.5 1,2,3-benzotriazole 0.1- 1.0 5- (or 6-)bromobenzotriazole 0.1- 1.0 5-(or 7-) nitroindazole 0.1- 0.52-mercaptobenzothiazole 0.1- 0.5 Z-mercaptobenzoxazole 0.1- 0.5Z-aminubenzothiazole 0.1- 1.0 5-aminotetrazole 0.1- 1.0 Thiobenzanilide0.1- 0.5 -2-acetylaminobenzothiazole 0.1- 0.5

The compounds may be added as noted above.

Example 3 The solid chemicals either mixed or unmixed and packaged forlater dissolving-in a liter of water to make an ammoniacal hypoeliminator bath, may contain 5 to 30 grams of 2-amino-2-methyl-1,3-propandiol and one of the addition substances shown inExample 2, such as 1 to grams of potassium bromide.

The 2-amino-2-methyl-1,3-propandiol compound may be replaced by asimilar quantity of a polyalkylene polyamide such as piperazine,di-isopropanolamine, or other solid water soluble alkaline reactingamine or substituted amine the nor-. mal solutions of which give a pHvalue in the range 9.5-12.0.

As another alternative for the solid amine, a water soluble amine saltpackaged to be used in conjunction with an inorganic alkali but notnecessarily mixed with it may be employed to form a solution. In thismanner amines which are not solid at ordinary temperatures may begenerated in solution by the addition of alkalies such as sodiumcarbonate, trisodium phosphate, sodium hydroxide, lithium hydroxide,etc. Ammonium salts such as the chloride and sulfate may also be used inthe same manner as the amine salts in conjunction with the inorganicalkalies.

Example 4 Grams Diethylamine' hydrochloride 11 Trisodium phosphate(cryst.) 38

These solid chemicals may be placed in separate compartments of a2-compartment package. Either compartment may contain 1.0 gram ofpotassium iodide. The chemicals of the two compartments are for thepreparation of one liter of hypo eliminator solution.

Example 5 A concentrated solution for marketing to be diluted with waterfor use in preparing one liter of hypo eliminator solution may contain:

Grams Ethanolamine 10- Hydrobromic acid 1- 5 Hydriodic acid 0.2-1.5

The term ammoniacal as used herein is not intended to limit the scope ofmy invention to ammonia or ammonia-peroxide hypo eliminator solutionsand refers to the use of ammonia or amines such as ethyl or butyl amine,ethanolamine, diethanolamine, ethylenediamine, diaminopropanoi,diethylamine, piperidine, morpholine, cyclohexylamine, benzylamine,triethylamine, and water soluble derivatives which may be either liquidsor solids at ordinary temperatures and characterized by the fact thattheir 0.1

normal solutions give a pH value of 9.5 to 12.0.

One theory of the function 01' the compounds used in the ammoniasolutions appears to be that they prevent solubilizing or changing thesurface of the silver images. Thus, sodium chloride is not suitable foruse in the solutions of my invention since silver chloride is readilysoluble in ammonia. In the ammoniacal peroxide solutions of my inventionthe compounds appear to precipitate the silver of silver-thiosulifatecomplexes and delay or prevent both its reduction to silver and theformation of silver sulfide on the image grains. The addition compoundsare likewise efiective in alkaline and alkalin peroxide hypo eliminatorsolutions containing no ammonia or amine.

It is to be understood that the disclosure herein is by way of exampleand that I consider as included in my invention all modifications andequivalents falling within the scope of the appended claims.

What I claim is:

l. The method of elimination of hypo from photographic silver imageswhich comprises treating said images with an ammoniacal peroxidesolution of a heterocyclic nitrogen compound forming a substantiallyinsoluble salt with silver in ammoniacal solution.

2. The method of elimination of hypo from photographic silver imageswhich comprises treating said images with an ammoniacal peroxidesolution of 6-nitrobenzimidazoie.

3. The solid chemicals packaged for use in making an ammoniacal hypoeliminator bath by dissolving in water for treatment of photographicsilver images comprising a solid alkaline reacting water soluble amineand a heterocyclic nitrogen compound forming a substantially insolublesalt with silver in ammoniacal solution.

4. The solid chemicals packaged for use in making an ammoniacal hypoeliminator bath by dissolving in water for treatment of photographicsilver images comprising a solid alkaline react ing water soluble amineand a derivative of benzothiazole.

5. The method of elimination of hypo from photographic silver imageswhich comprises treating said images with an ammoniacal solution of aheterocyclic nitrogen compound forming a substantially insoluble saltwith silver in ammoniacal solution.

6. The packaged chemicals for use in making in the range an ammoniacalhypo elimination bath by the addition of water for treatment ofphotographic silver images comprising an alkaline reacting water solubleamine and a heterocyclic nitrogen compound forming a substantiallyinsoluble salt with silver in ammoniacal solution.

LOWELL E. MUEHLER.

l I CERTIFICATE OF CORRECTION. Patent No. 2,558,665. v January )4,191111..

LOWELL E. MUEHLER.

It is hereby certified that error appears in the printed specificationof the abovenumbered patent requiring correction as follows: Page 1,sec-- 0nd column, line 214,, Example 1, for "reactions" read--reactants-; page 2, first column, line 12, Example 5, for "polyamide"read --polyamine-;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 29th day-of February, A. D. 19%.

Leslie Frazer Acting Commissioner of Patents.

